Data Cart

The NCHS website provides the following description of the NDI:

The NCHS has assisted researchers by linking the records for NHIS survey participants with the NDI. The mortality variables in the NHIS public use files (and in IHIS) are based on results from probabilistic matches between NHIS records and NDI death certificate records. The NCHS website explains:

For additional information, see the technical documents from NCHS on the creation and analysis of the NHIS Linked Mortality Files.

Because adult survey participants who provided insufficient data for linking may differ from those who provided enough data for linking, ignoring the ineligible adult respondents (IHIS code 3 in MORTELIG) could lead to biased mortality analysis. To correct this bias, NCHS developed eligibility-adjusted weights: MORTWT, available for 1986-2004, for use with variables from the NHIS person files, and MORTWTSA, available for 1997-2004, for use with variables from the sample adult files. When analyzing NHIS variables from the person files in conjunction with mortality variables, users should employ MORTWT (rather than the standard person weight, PERWEIGHT). When analyzing variables from the sample adult files in conjunction with mortality variables, users should employ MORTWTSA (rather than the standard sample weight, SAMPWEIGHT).

The other mortality variables included in IHIS are the following:

• MORTSTAT (Final mortality status)

• MORTDODY (Year of death)

• MORTDODQ (Quarter of death)

• MORTUCOD (Underlying cause of death)

• MORTDIAB (Multiple cause of death flag, diabetes as a contributing factor)

• MORTHIPFX (Multiple cause of death flag, hip fracture as a contributing factor)

• MORTHYPR (Multiple cause of death flag, hypertension as a contributing factor)

• MORTCMS (Mortality status obtained from Centers for Medicaid and Medicare Services)

• MORTNDI (Mortality match with National Death Index)

• MORTSSA (Mortality status obtained from Social Security Administration)